Greetings,
Mr. K. Strange. There's no wiring on that side of the engine that could have been knocked loose and even IF wiring was knocked loose, if a diesel engine turns over, it usually starts. Your mechanic basically did exactly the same thing all of us Lehman owners do every oil change (take out plug, drain, replace plug, refill with 1 pint) so it should fire right up.

How good is this mechanic? Might he have damaged the Simms pump in some way?

If the new plug is too long it will jam on the cams that are in the pump. Does this mechanic have a Simms background? Since this is all gear driven, it would prevent the engine from turning over. I think the mechanic just bought you a new pump.

When I just tapped mine for a 3/8 bolt, I repeatedly probed the inside of the pump to see where an obstruction might be and did not feel anything straight up or just off to the side for at least an inch...which was 1/4 inch longer than anything I planned and probably another inch to spare.

Could be a different pump but all the pics I have seen look pretty much the same.

the sims pump was removed and had to be rebuilt.... the pump is now back in the boat and tested. I will give it a run this weekend as the mechanic will do a check and readjust after 10 hours... so hopefuly it will start as it always did ... I'm sure it will
Kevin G
new Bern NC

yes the mechanic did come through... he removed the simms pump and had it rebuilt and intstalled it back onto the engine...I do believe he is a very honest and a competent mechanic ... he did right by me... I go to the forum to get advice as most folks do ...